A motor vehicle may include one or more cameras for capturing images of the environment around the vehicle. The images may be used for detecting lanes on the road or traffic signs or may provide the driver with a view of the immediate vicinity of the vehicle. The view of the immediate vicinity of the vehicle may be used to assist the driver when parking the vehicle or may be used to improve safety as the driver is able to view areas which are screened from him in a normal driving position. Hazards or possible hazards may also be detected from the captured image or images and then provide the driver with a warning or the information may be used in connection with driver assistance systems to actively take control of the vehicle and avoid the hazard.
Typically several cameras, for example four, are provided on the vehicle. The images from each of the cameras may be combined to provide a 360° image in the form of a top view, also denoted as a bird's eye view, or a panoramic view. Typically, the images from adjacent cameras, for example a front camera and a side camera, overlap with one another in order to provide an uninterrupted 360° view. If the brightness and color of the images from adjacent cameras differ, the resulting combined image may be difficult to discern.
The published patent application JP 2007-323587 A discloses an image composition device in which a mean value of pixels in the image overlapping areas of adjacent cameras is calculated to find gain unifying hues of the adjacent camera images. A correction gain calculation unit adjusts a hue to those of surrounding camera images to reduce the difference of correction gain values between adjacent camera images in order to combine the images into an easily visible composite image with a uniform hue.
However, since cameras on vehicles are typically video cameras capturing a number of images per second, providing correction gain values for each of the images requires certain processing resources which may not be available in the vehicle.